Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
287 ACUS01 KWNS 252010 SWODY1 SPC AC 252009 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0309 PM CDT Sat May 25 2024 Valid 252000Z - 261200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR MUCH OF OKLAHOMA...CENTRAL AND EASTERN KANSAS...SOUTHWEST AND SOUTH-CENTRAL MISSOURI...AND FAR NORTHERN TEXAS.... ...SUMMARY... An outbreak of severe thunderstorms is possible from late afternoon into tonight over parts of the central and southern Plains. A few long-lived supercells capable of intense tornadoes may occur. Giant hail and destructive wind gusts are also expected. Expanded all outlook categories eastward across Missouri based on increased confidence in multiple supercells across southern Kansas congealing into a cluster during the overnight period. RAP forecast soundings show extreme buoyancy (3500+ J/kg) continuing through the overnight period amid robust low-level moisture and steep mid-level lapse rates. A forward propagating cluster capable of severe wind gusts and tornadoes is expected to persist through 12Z Sunday. The only other change was to expand the moderate farther south into north Texas based on recent observational trends. Numerous supercells have formed west of this area and should persist as they continue east into a high theta-e airmass. Large hail will be the primary threat with an increasing tornado threat near 00Z as the low-level jet intensifies. No changes were made to the primary risk area. See MCD #954 for additional discussion of the threat in this area. ..Bentley.. 05/25/2024 .PREV DISCUSSION... /ISSUED 1134 AM CDT Sat May 25 2024/ ...Central/Southern Plains... Overall, little change was made to the ongoing outlook with this update, with the primary change being an eastward expansion of the Enhanced/Level 3 Risk over portions of North Texas based on the 12z HREF guidance. Strong low-level moisture advection continues across northwest TX/southern OK at 16z, and this trend is expected to continue and expand north into southern KS with time. Strong diurnal heating amid a rapidly moistening boundary layer and steep mid-level lapse rates will yield strong/extreme MLCAPE this afternoon along and east of the dryline. Initial supercell development is anticipated late this afternoon across northwest TX, where strong diurnal heating should continue to erode CINH. Isolated intense supercell development is also expected farther north along the dryline towards 00z across OK/southern KS, where rapidly returning moisture into a well-heated boundary layer coincident with a strengthening low-level jet should contribute to a high-end/all hazards severe risk. Additional isolated supercell development is also anticipated near the warm front across northern KS. The primary uncertainty remains storm coverage, with 12z high-res guidance continuing to exhibit a range of solutions. As mid-level flow increases and a shortwave trough approaches, an extremely favorable thermodynamic and kinematic environment is expected to be in place across the Enhanced/Moderate Risk areas from late afternoon into tonight. The risk for strong/intense tornadoes, very large to giant hail, and significant severe winds remains evident. ...Southeast... Rapid diurnal heating of a moist low-level air mass is occurring downstream of ongoing convection, and temperatures have warmed well into the 80s as of 16z. Strong thunderstorms over southeast AL are expected to continue moving southeast within a moderately-sheared/northwest flow environment and be capable of strong/possibly damaging gusts and severe hail. A small Slight/Level 2 Risk has been introduced with this outlook, where the more favorable overlap of 35 kts of northwesterly effective shear and moderate/strong instability will exist. ...Lower Great Lakes/upper Ohio Valley... Widely scattered to scattered thunderstorms are expected near the cold front this afternoon, and along a nearly parallel, prefrontal trough/convergence zone. Storms should move eastward/southeast and persist into early evening. Aside from lift along those boundaries, activity will be supported by diurnally weakened MLCINH, with surface dewpoints in the upper 50s to mid 60s F contributing to around 1500 J/kg MLCAPE. Weak low-level flow and nearly unidirectional low/middle-level wind profiles will tend to limit shear, however sufficient cloud-bearing layer shear should exist to support multicell storm structures. Damaging gusts and isolated hail will be possible from the best-organized convection. $$